The present invention deals with novel compounds, their applications and a process their preparation. The compounds are novel amphoteric surfactants that contain a hydroxyl group and two carboxylic groups per hydroxyl group. The compounds have a unique structure, having multiple carboxyl groups on each amino group. The utility for these novel polymers is as softening, anti-tangle, and conditioning agents for use in personal care, textile and related applications. The properties of these novel amphoteric polymeric compositions which makes them well suited for these applications is the fact that they are substantive to fibers, hair and skin and also very mild to the skin and eyes.
Aminocarboxylic amphoteric surfactants have been known and used commercially for many years. Perhaps the most important early patent on the production of these materials is U.S. Pat. No. 2,195,974 to Reppe et al. The patent, issued in May 1936 and assigned to I. G. Farben, discloses the reaction of acrylic acid, methacrylic acid and ammonia or organic amines at temperatures at which amides do not form. The patent described many reaction conditions in addition many solvents were described ranging from water to other protic solvents. Reppe also describes many so-called xe2x80x9cacrylic sourcesxe2x80x9d, which are suitable as raw materials for preparation of this class of amphoteric surfactants.
The surfactant properties of aminocarboxylic acids and salts are likewise well known to those skilled in the art. Over the years, these compounds have been found to have limited usefulness as foaming agents and detergents in some applications. The compounds have not enjoyed wider use in other applications, due to the fact the prior art compounds lack compatibility with anionic surface active agents, are not mild when applied to the eye and skin
U.S. Pat. No. 3,417,136 issued to Hovden Dec. 17, 1968, attempts to develop a product with increased water solubility by incorporating an ether function into the molecule. Hovden states prior to his invention, the known aminocarboxylic acid surfactant compounds have a lesser water solubility than is desired in some applications. Further, he states many of these compounds do not have as great a wetting power as might be desired for certain applications. This is also a function of water solubility.
While Hovden""s invention solved the difficulty of obtaining a series of products that are more water soluble and have improved wetting properties, it remained a problem to produce products with the desired anionic compatibility and mildness and electrolyte compatibility.
It is the object of this invention to produce novel amphoteric compounds that have improved are highly substantive to hair, skin and fibers, have low irritation properties when placed on the skin or in the eyes, and are compatible with anionic surfactants. This improved performance relates to the fact that the products of this invention (a) contain fatty amino groups and (b) contain a poly carboxy functionality which results amphoterics with unique solubility, and emulsification properties in a variety of solvents. These materials also provide stable copious foam and much improved detergency properties over traditional amino proprionates.
Another object of the invention is to provide a novel class of amphoteric compounds that exhibit outstanding surface-active properties.
Still another object of the invention is a process for the treatment of skin, hair and fibers with an effective conditioning amount of the compounds of the invention.
Other objects of the invention will become clear from the disclosure.
The compounds of the present invention are poly-carboxy containing amphoteric surfactants. They compounds of the present invention conform to the following structure; 
R1 is selected from the group consisting of alkyl having from 6 to 20 carbon atoms and
xe2x80x83R4xe2x80x94Oxe2x80x94(CH2)3xe2x80x94
R4 is alkyl having from 6 to 20 carbon atoms;
R2 is 
M is a cation needed for charge balance and is selected from the group consisting of Na, K, Li and H;
R3 is selected from the group consisting of H and 
The compounds of the present invention are multi-carboxylates. In one instance a di carboxylate that has a secondary amine present. Typical of this type of compound is as follows: 
In another preferred instance they are tetra carboxylates that have a tertiary amine present. 
In this latter case the tetra carboxylate results in an amphoteric surfactant that is not sensitive to Ca ion. Standard amphoterics conform to the following structure:
R-N-(CH2CH2C(O)OH)2
These compounds have only two carboxyl groups that branch at nitrogen, lack the hydroxy group and consequently have poor hard water tolerance.
By properly selecting the number of carbon atoms in the alkyl or alkyl ether group a product that has the proper balance between water-soluble and oil soluble groups is attained.
In a preferred embodiment R1 is of alkyl having from 6 to 20 carbon atoms
In a preferred embodiment R1 is R4xe2x80x94Oxe2x80x94(CH2)3xe2x80x94.
In a preferred embodiment R1 is M is H.
In a preferred embodiment R1 is M is Na.
In a preferred embodiment R1 is M is K.
In a preferred embodiment R1 is M is Li.
In a preferred embodiment R3 is H.
In a preferred embodiment R3 is 
In a preferred embodiment R1 is of alkyl having 6 carbon atoms.
In a preferred embodiment R1 is of alkyl having 8 carbon atoms.
In a preferred embodiment R1 is of alkyl having 10 carbon atoms.
In a preferred embodiment R1 is of alkyl having 12 carbon atoms.
In a preferred embodiment R1 is of alkyl having 14 carbon atoms.
In a preferred embodiment R1 is of alkyl having 16 carbon atoms.
In a preferred embodiment R1 is of alkyl having 18 carbon atoms.
In a preferred embodiment R1 is of alkyl having 20 carbon atoms.
In a preferred embodiment R4 is of alkyl having 6 carbon atoms.
In a preferred embodiment R4 is of alkyl having 8 carbon atoms.
In a preferred embodiment R4 is of alkyl having 10 carbon atoms.
In a preferred embodiment R4 is of alkyl having 12 carbon atoms.
In a preferred embodiment R4 is of alkyl having 14 carbon atoms.
In a preferred embodiment R4 is of alkyl having 16 carbon atoms.
In a preferred embodiment R4 is of alkyl having 18 carbon atoms.
In a preferred embodiment R4 is of alkyl having 20 carbon atoms.